Williams SA et al. (2000) Int J Parasitol "The filarial genome project: analysis of the nuclear, mitochondrial and endosymbiont genomes of Brugia malayi."

Daub J, Blaxter ML, Foster J, Guiliano D, Lizotte-Waniewski MR, Scott AL, Williams SA, Slatko B

[Int J Parasitol, 2000]

The Filarial Genome Project (FGP) was initiated in 1994 under the auspices of the World Health Organisation. Brugia malayi was chosen as the model organism due to the availability of all life cycle stages for the construction of cDNA libraries. To date, over 20000 cDNA clones have been partially sequenced and submitted to the EST database (dbEST). These ESTs define approximately 7000 new Brugia genes. Analysis of the EST dataset provides useful information on the expression pattern of the most abundantly expressed Brugia genes. Some highly expressed genes have been identified that are expressed in all stages of the parasite's life cycle, while other highly expressed genes appear to be stage-specific. To elucidate the structure of the Brugia genome and to provide a basis for comparison to the Caenorhabditis elegans genome, the FGP is also constructing a physical map of the Brugia chromosomes and is sequencing genomic BAC clones. In addition to the nuclear genome, B. malayi possesses two other genomes: the mitochondrial genome and the genome of a bacterial endosymbiont. Eighty percent of the mitochondrial genome of B. malayi has been sequenced and is being compared to mitochondrial sequences of other nematodes. The bacterial endosymbiont genome found in B. malayi is closely related to the Wolbachia group of rickettsia-like bacteria that infects many insect species. A set of overlapping BAC clones is being assembled to cover the entire bacterial genome. Currently, half of the bacterial genome has been assembled into four contigs. A consortium has been established to sequence the entire genome of the Brugia endosymbiont. The sequence and mapping data provided by the FGP is being utilised by the nematode research community to develop a better understanding of the biology of filarial parasites and to identify new vaccine candidates and drug targets to aid the elimination of human filariasis.

Desjardins CA et al. (2013) Nat Genet "Genomics of Loa loa, a Wolbachia-free filarial parasite of humans."

Dunning Hotopp JC, Goldberg JM, Fan L, Haas BJ, Zucker J, Cerqueira GC, Saif S, Wortman JR, Zeng Q, Fink DL, Russ C, Birren BW, Levin JZ, Ribeiro JM, Nutman TB, Desjardins CA

[Nat Genet, 2013]

Loa loa, the African eyeworm, is a major filarial pathogen of humans. Unlike most filariae, L. loa does not contain the obligate intracellular Wolbachia endosymbiont. We describe the 91.4-Mb genome of L. loa and that of the related filarial parasite Wuchereria bancrofti and predict 14,907 L. loa genes on the basis of microfilarial RNA sequencing. By comparing these genomes to that of another filarial parasite, Brugia malayi, and to those of several other nematodes, we demonstrate synteny among filariae but not with nonparasitic nematodes. The L. loa genome encodes many immunologically relevant genes, as well as protein kinases targeted by drugs currently approved for use in humans. Despite lacking Wolbachia, L. loa shows no new metabolic synthesis or transport capabilities compared to other filariae. These results suggest that the role of Wolbachia in filarial biology is more subtle than previously thought and reveal marked differences between parasitic and nonparasitic nematodes.

Hertz-Fowler C et al. (2008) Nat Rev Microbiol "Sequence data swell for nematodes."

Hertz-Fowler C, Pain A

[Nat Rev Microbiol, 2008]

With more than 80,000 described species that are extremely diverse in terms of ecology and biology, the Nematoda phylum is one of the most common animal phyla. This month's Genome Watch describes genomes of several nematodes, including that of the human filarial parasite Brugia malayi.

Fauver JR et al. (2019) Sci Rep "De novo Assembly of the Brugia malayi Genome Using Long Reads from a Single MinION Flowcell."

Weil GJ, Martin J, Fauver JR, Mitreva M, Fischer PU

[Sci Rep, 2019]

Filarial nematode infections cause a substantial global disease burden. Genomic studies of filarial worms can improve our understanding of their biology and epidemiology. However, genomic information from field isolates is limited and available reference genomes are often discontinuous. Single molecule sequencing technologies can reduce the cost of genome sequencing and long reads produced from these devices can improve the contiguity and completeness of genome assemblies. In addition, these new technologies can make generation and analysis of large numbers of field isolates feasible. In this study, we assessed the performance of the Oxford Nanopore Technologies MinION for sequencing and assembling the genome of Brugia malayi, a human parasite widely used in filariasis research. Using data from a single MinION flowcell, a 90.3Mb nuclear genome was assembled into 202 contigs with an N50 of 2.4Mb. This assembly covered 96.9% of the well-defined B. malayi reference genome with 99.2% identity. The complete mitochondrial genome was obtained with individual reads and the nearly complete genome of the endosymbiotic bacteria Wolbachia was assembled alongside the nuclear genome. Long-read data from the MinION produced an assembly that approached the quality of a well-established reference genome using comparably fewer resources.

Tuteja R et al. (2012) Gene "Genome wide computational analysis of Brugia malayi helicases: a comparison with human host."

Saxena JK, Tuteja R, Ansari A, Suthar MK

[Gene, 2012]

The availability of Brugia malayi genome sequence has paved ways for the search of homologues for a variety of genes. Helicases are ubiquitous enzymes involved in all the nucleic acid metabolic pathways and are essential for the development and growth. The genome wide analysis of B. malayi for different helicases showed the presence of a number of DEAD box helicases, 7 DEAH box helicases, RecQ helicases, repair helicases, super killer helicases, MCM2-7 complex, Rad54 and two subunits of Ku helicase. The comparison of protein sequence of each helicase with its human counterpart indicated characteristic differences in filarial helicases. There are noticeable differences in some of the filarial helicases such as DHX35, RecQL1 and Ku. Further characterization of these helicases will help in understanding physiological significance of these helicases in filarial parasites, which in future can be utilized for chemotherapy of parasitic infection.

Dissanayake S (2000) Int J Parasitol "Upregulation of a raf kinase and a DP-1 family transcription factor in epidermal growth factor (EGF) stimulated filarial parasites."

Dissanayake S

[Int J Parasitol, 2000]

Previously we have shown that in the filarial parasite Brugia malayi, stimulation with murine epidermal growth factor (EGF) upregulated the expression of the nuclear GTPase, Ran. In this paper we provide further evidence that filarial parasites possess the ability to respond to mammalian EGF. Stimulation of B. malayi microfilariae with EGF increased transcription of a Raf kinase, increased the physical interaction between Ran and at least eight unidentified proteins, abolished the association of a putative EGF receptor with the nuclear GTPase Ran and enhanced phosphorylation of native microfilarial proteins. In the cattle filarial parasite Setaria digitata, stimulation of adult worms with EGF was probably responsible for up-regulation of a DP-1 family transcription factor. These data suggest that filarial parasites possess the ability to respond to mammalian EGF and that mammalian growth factors may regulate developmental maturation of filarial parasites.

Terhell AJ et al. (2002) Parasitology "Regulation of anti-filarial IgE by infection pressure."

Mangali A, Yazdanbakhsh M, Van Oortmarssen GJ, Terhell AJ, Stolk WA, Haarbrink M

[Parasitology, 2002]

In lymphatic filariasis, specific IgG4 responses to the parasite and their relationship with infection have been studied extensively, but only a few studies have concentrated on anti-filarial and total IgE. Here we have investigated the role of filarial infection pressure on production of IgE by considering length of exposure (age), filarial endemicity and parasitological status. Antibody levels were determined in 366 individuals, who were resident in 3 villages in South-Sulawesi, Indonesia, with varying degrees of filarial transmission intensity, as indicated by the prevalence of Brugia malayi microfilaraemia (0.7%, 9% and 32%, respectively). Anti-filarial IgE levels were significantly lower in the low transmission village than in the areas with intermediate and high filarial transmission; however, in the latter village a remarkable suppression of specific IgE was found. Microfilaria-positive individuals showed elevated levels of total IgE, but suppression of specific IgE, which has been reported before. Taken together, these observations suggest that 2 opposing mechanisms regulate anti-parasite IgE expression: increasing experience of filarial infection stimulates specific IgE, but antibody levels become specifically suppressed when microfilariae or adult worms develop. Using a simple mathematical model, we illustrate how anti-filarial IgE increases with parasite antigen up to a threshold level, but levels off and becomes down-regulated after the threshold is exceeded.

Cheirmaraj K et al. (1990) J Immunoassay "Diagnostic use of polyclonal antibodies raised in mouse ascitic fluid in bancroftian filariasis."

Reddy MV, Cheirmaraj K, Harinath BC

[J Immunoassay, 1990]

Polyclonal antibodies were produced against Brugia malayi adult antigens (BmA (PBS) SAg and BmA (SDS) SAg) in mouse ascitic fluid by immunising Balb/c mice intraperitoneally with high ratio of adjuvant to immunogen. The diagnostic use of these antibodies in detecting circulating filarial antigen in bancroftian filariasis was studied by sandwich enzyme-linked immunosorbent assay (sandwich ELISA) using stick assay system. Both antibodies raised against PBS and SDS soluble antigens were found to be equally sensitive and relatively specific in detection of circulating filarial antigen. When anti BmA (PBS) SAg antibody was used in sandwich ELISA, 90% of microfilaraemic sera, 30-40% of acute and sub acute filarial sera, 20% of chronic filarial sera, 7% of endemic normal sera and none of 15 non-endemic normal sera were positive for filarial antigen. Using anti BmA (SDS) Sag antibody, 93% of microfilarial sera, 40% of acute and sub acute filarial sera, 20% of chronic filarial sera and none of 15 endemic and non-endemic normal sera showed the presence of filarial antigen. The filarial antigen detection using anti BmA S Ag antibodies produced in mouse ascitic fluid in sandwich ELISA may be useful in detection of active stage (microfilaraemia) of infection.

Stein LD (1999) Trends Genet "Internet access to the C. elegans genome."

Stein LD

[Trends Genet, 1999]

In December 1998, the genome of the small soil-dwelling nematode Caenorhabditis elegans became the most recent model to fall to the collective efforts of the Genome Project, its complete 97 Mbp genome taking its place alongside those of Saccharomyces cerevisiae, Escherichia coli and numerous other microorganisms. The availability of the C. elegans sequence means that, for the first time, the complete genome of a fully functional multicellular animal is available to the scientific community, along with a rich infrastructure of genetic, behavioral, physiological and developmental data about the organism.

Turner JD et al. (2018) PLoS Pathog "Interleukin-4 activated macrophages mediate immunity to filarial helminth infection by sustaining CCR3-dependent eosinophilia."

Guimaraes AF, Allen JE, Furlong-Silva J, Pionnier N, Steven A, Cook DAN, Sjoberg H, Van Rooijen N, Cross S, Turner JD, Jenkins SJ, Taylor MJ, Halliday A

[PLoS Pathog, 2018]

Eosinophils are effectors in immunity to tissue helminths but also induce allergic immunopathology. Mechanisms of eosinophilia in non-mucosal tissues during infection remain unresolved. Here we identify a pivotal function of tissue macrophages (M) in eosinophil anti-helminth immunity using a BALB/c mouse intra-peritoneal Brugia malayi filarial infection model. Eosinophilia, via C-C motif chemokine receptor (CCR)3, was necessary for immunity as CCR3 and eosinophil impairments rendered mice susceptible to chronic filarial infection. Post-infection, peritoneal M populations proliferated and became alternatively-activated (AAM). Filarial AAM development required adaptive immunity and interleukin-4 receptor-alpha. Depletion of M prior to infection suppressed eosinophilia and facilitated worm survival. Add back of filarial AAM in M-depleted mice recapitulated a vigorous eosinophilia. Transfer of filarial AAM into Severe-Combined Immune Deficient mice mediated immunological resistance in an eosinophil-dependent manner. Exogenous IL-4 delivery recapitulated tissue AAM expansions, sustained eosinophilia and mediated immunological resistance in M-intact SCID mice. Co-culturing Brugia with filarial AAM and/or filarial-recruited eosinophils confirmed eosinophils as the larvicidal cell type. Our data demonstrates that IL-4/IL-4R activated AAM orchestrate eosinophil immunity to filarial tissue helminth infection.